Vauxhall Astra Throttle body/ Engine issues?

[Amilli09]

I have a 02 plate Vauxhall Astra sxi 1.6. The problem started with the service light being on and it going into limp mode when stuck in traffic, i hooked it up to a diagnostic and it stated it was the throttle peddle running at 30% instead of 100%, so i replaced the peddle and the problem continued. The diagnostic then stated it was the electronic throttle body (which i am yet to fit). But now all of a sudden the engine light is on and the car had a hard time starting (it has been v cold the past two nights). The engine sounds like it is ticking and it is revving by itself when idle. Do you think these two issues are related? How would you suggest i solved these two issues? And off the top of your head can you give an estimate in how much getting it all done might cost?

[Amilli09]

I haven't done that no, would that be difficult to do? what tools would i need? Thanks